The JAR exams took me about 18 months to complete. I had a couple of months break in the middle due to a new endorsement. I did the Aus ATPL back when you had to do all exams in a two day sitting. I found them harder because You had to know everything! for two days worth of exams. That said however the JAR exams want you to know even more, but the knowledge is divided into 14 exams with some topics being covered in multiple exams. Still very doable but as stated by someone else, you can't muck about.
Practical conversion was 2 sim sessions (one prep, one JAR ATPL skills test)